Fig. 4
Effect of walking bout duration on the relative errors (\(\varepsilon\)) in a step duration, b cadence, and c step length estimations. For each parameter and the selected algorithms (ICDA for all cohorts; CADB for the congestive heart failure (CHF), chronic obstructive pulmonary disease (COPD), healthy adults (HA), multiple sclerosis (MS) and Parkinson’s disease (PD) cohorts; CADC for the proximal femoral fracture (PFF) cohort; SLA for CHF, COPD, HA, PFF and PD; and SLB for MS), the individual filled circles (n) represent the relative error for each WB, colour coded according to the walking speed measured for that specific bout. The empty grey circles indicate the median relative errors quantified in subsequent separate walking bout duration (wbd) windows of 2 s. Grey intensity represents the weight associated to the relevant observation, calculated as the ratio between the number of points in a given walking bout duration window and the total number of points, in the best-fit approach; a darker grey represents a larger weight. The black continuous lines and equations are the result of a best-fit approach used to determine the association between walking bout duration and the median errors; R2 values are also shown. The horizontal black dash-dotted lines visually indicate the relative error thresholds of 10% and 20%. For a clear visualization of the results, 95% of the walking bout duration have been reported